ch 10 dna the chemical nature of the gene

genetic material must

contain complex info, large amounts
replicate faithfully
encode phenotype (rna, protein)
capacity to vary

transformation

test iiis virulent, iir nonvirulent, iiis heat killed, mix iir and heat killed iiis virulent
mice with mix die, because of transformation, acquiring genetic virulence of heat kill iiis, transformation produce permanent genetic change in bacteria

transforming principle

is dna!!!!! resides in dna!!!! genetic info resides in dna!
tested by using 3 diff enzymes RNase Protease and DNase on iiis virulent, only DNase killed it

virus/phages and dna as genetic material

t2 bacteriophage, phage coat is protein and inside is dna
infect w ecoli in sulfur and in phosphorus
infect with new ecoli
shear off protein coats, separate protein w centrifuge, only phosphorus was shown in new ecoli. and dna has phosphorus

dna structure

a bonds with t
g bonds with c
two strands nucleotides running antiparallel, wind around for right habd helix
sugar phosphate outside and base inside

rna as genetic material

tobacco mosaic virus tmv
single molecule rna around helical cylinder of protein
separate rna and protein of tmv, remix of different strains, obtain intact infenctions viral particles. therefore rna is genetic material

primary structure of dna

sugar: 5 carbons, 2’ has h whereas rna has oh
rna therefore more react and less stable
base: purine 2 ring AG or pyrmadine 1 ring CTU, covalent bond with 1’ sugar
phosphate: phosphorus and 4 oxygen, negative, so dna is acidic, bonded to 5’ sugar

secondary structure dna

3d configuration, helical
double helix: antiparallel, h bonds link bases and weaker than covalent, a/t 2 bonds and c/g 3 bonds

bdna is normal, lot of water and no unusual base sequences
adna is less water, so shorter and wider
zdna is when a lot of alternating c and g, backbone zigzag, so its opposite bdna

special structures in dna and rna

secondary structure: hairpin
paird bases in stem and intervening unpaired bases in loop
rna have lots to fold into complex structures
primary structure: dna methylation, add ch3 to bases
bacteria dna methylated to distinguish from foreign viral dna, bacteria use protein to cut unmethyl dna
metyhl in eukary is low level transcrip
a/c common methyl in bacteria
in eukary c is methyl but varies like less in humans and more in plants